4.2.1 Biodiversity Flashcards
what is biodiversity?
the variety of species of living organisms in an area
species
a group of similar organisms able to reproduce to give fertile offspring
habitat
the area inhabited by a species
includes physical factors - soil and temperature range
and living factors - availability of food and presence of predators
levels of biodiversity - habitat diversity
the no. of different habitats in an area
levels of biodiversity - species diversity
the no. of different species (species richness) and the abundance of each species (species evenness) in an area
levels of biodiversity - genetic diversity
the variation of alleles within a species (or a population of species)
eg. different breeds within a species
how is sampling used to measure biodiversity?
in most cases too time consuming to count every organism so a sample is taken and an estimation is made.
- choose an area to sample
- count the no. of individuals of each species
- repeat this process - take as many samples as possible (gives a better estimate)
- use results to estimate the total no. of individuals or the total no. of different species in the habitat being studied
when sampling different habitats and comparing them use the same sampling technique
sampling methods - plants
frame quadrat
sampling methods - flying insects
sweep net
sampling methods - ground insects
pitfall trap
sampling methods - aquatic animals
a net
how do you avoid bias when sampling?
use random sampling
- make a grid using measuring tapes and use a random number generator
when do you use non-random sampling?
when there’s lots of variety in the distribution of species in the habitat and you want to make sure all the different areas are sampled
non-random sampling - systematic
when samples are taken at fixed intervals, often along a line
eg. quadrats could be placed along a line, a transect, from an areas of shade the corner of the field to the middle
non-random sampling - opportunistic
when samples are chosen by the investigator
simple to carry out but data is biased
non-random sampling - stratified
when different areas in a habitat are identified and sampled separately in proportion to their part of the habitat as a whole
eg. a heathland may have patched of gorse in it - the heath and gorse areas would be sampled separately according to how much of each there was in the habitat
species richness
the no. of different species in an area
the higher the no. of species the greater the species richness
how is species richness measured?
by taking random samples of a habitat and counting the number of different species
species evenness
a measure of the relative abundance of each species in an area
the more similar the population size of each species, the greater the species evenness
how is species evenness measured?
by taking random samples of a habitat, and counting the number of individuals of each different species
the greater the species richness and evenness….
…the higher the biodiversity
how do you measure diversity?
Simpson’s index of diversity D = 1 - ( sum (n/N)^2 )
n = total no. of individuals of one species
N = total no. of organisms of all species
takes into account both richness and evenness
the closer D=1, the more diverse
genetic diversity - what if too low?
if a population had low genetic diversity, they might not be able to adapt and change in the environment and the whole population could be wiped out by a single event (disease)
what population have low genetic diversity?
isolated populations
- bred in captivity
zoos, pedigree animals, rare breeds
how do you measure genetic diversity?
genetic polymorphism
- alleles are different versions of a gene
- alleles of the same gene are found at the same point (locus) on a chromosome
- polymorphism describes a locus that has two or more alleles
- this can be used to work out genetic diversity
EQUATION:
proportion of polymorphic gene loci = no. of polymorphic gene loci / total no. of loci
What can calculations of genetic diversity be used for?
used to monitor the genetic diversity of (isolated) populations over time
efforts can be made to increase the genetic diversity of the population if needed
- breeding programs in zoos are very closely managed to maximise genetic diversity
Factors affecting biodiversity
human population growth
agriculture (monoculture)
climate change
Factors affecting biodiversity - human pop. growth
- habitat loss - human development is destroying habitats eg. amazon rainforest to make way for grazing and agriculture —> decreases habitat diversity
- over-exploitation - a greater demand for resources (food, water, energy) means a lot of resources are being used up faster than they can be replenished. eg. industrial fishing —> decreases genetic diversity and species diversity
- urbanisation - sprawling cities and major road developments can isolate species, meaning populations are unable to interbreed —> decreases genetic diversity
- pollution - high amounts of pollutants can kill fish species or destroy habitats. eg. high levels of fertiliser flowing into a river —> decrease biodiversity
Factors affecting biodiversity - monoculture (in agriculture)
in order to feed the growing no. of people large areas of land are devoted to monoculture - growing a single variety of crop eg. in Africa palm oil plantations
—> leads to a decline in biodiversity because:
- habitat loss - land is cleared to make way for large fields –> reducing habitat diversity
- local and naturally occurring plants and animals are seen as weeds or pests and so are destroyed with pesticides and herbicides —> reducing species diversity
- heritage (traditional) varieties of crop are lost because they don’t make enough money and so are not planted any more —> reduces species diversity
Factors affecting biodiversity - climate change
- climate change is the variation in the earth’s climate - changes in temperature+rainfall patterns
- it occurs naturally, but scientific consensus is that the climate change we are experiencing now is due to humans increasing greenhouse emissions - enhancing the greenhouse effect
some places will get colder, some warmer, some wetter, some drier —> all affects global biodiversity
Factors affecting biodiversity - climate change impacts
most species need a particular climate to survive
- a change in climate may mean that an area previously inhabitable becomes uninhabitable (visa versa)
- this may cause an increase or decrease in the range of some species eg. the southern range limit of the Sooty Copper Butterfly has moved 60miles north in recent decades
- some species may be forced to migrate to a more suitable area, causing a change in species distributed –> migrations decrease biodiversity (in the areas they migrate from) and increase biodiversity in the areas they move to
- if there isn’t a suitable habitat to migrate to, the species is a plant so cant migrate or if the chane is too fast —> extinction (which decreases biodiversity). Eg. corals die if water temps. change by 1-2degrees
reasons to maintain biodiversity - ecological
- to protect keystone species
2. to maintain genetic resources
ecological reasons to maintain biodiversity - to protect keystone species
organisms in an ecosystem are interdependent - the loss of one species can have pretty drastic effects on an ecosystem
- disruption of food chains
- disruption of nutrient cycles
there are some species that many other species depend on - without them the ecosystem would change dramatically –> keystone species
- often predators but can also be modifiers
ecological reasons to maintain biodiversity - to maintain genetic resources
genetic resources refer to any material containing genes we find valuable
- crops, plants used for medicine, microorganisms used in industrial processes, or animal breeds
- genetic resources provide us with everyday products
- food and drink
- clothing
- drugs
- fuels
- other industrial material - many genetic resources are important to the global economy - trade
- genetic resources allow us to adapt to changes in the environment
- climate change = plants cant grow in the same areas –> could use genes from a plant that’s resistant to droughts and genetically engineer a drought resistant crop
reasons to maintain biodiversity - economic
to reduce soil depletion
- continuous monoculture involves planting the same crop in the same field without interruption
- this causes soil depletion because nutrients required by the crop are used up
- the economic costs of soil depletion:
- increased spending on fertilisers
- decreased yields (in the long run)
reasons to maintain biodiversity - aesthetic
- areas rich in biodiversity provide pleasant, attractive landscapes that people can enjoy by maintaining biodiversity we protect these landscapes
- the more biodiversity in an area the more visitors the area is likely to attract
- this also has economic advantages
in situ conservation - what?
on-site conservation
protecting species in their natural habitat
in situ conservation - methods
- establishing protected areas - national parks, wildlife reserves and marine conservation zones
- restrict; urban dev., industrial dev., farming/fishing - controlling/preventing the introduction of species that threaten local biodiversity
- protecting habitats - eg. controlling water levels to conserve wetlands and coppicing trees to conserve woodlands —> organisms continue to live in their natural habitat
- promoting particular species - protecting food sources or nesting sites
- legal protection to endangered species - illegal to poach
in situ conservation - advantages
- both species and habitat conserved
- larger populations can be protected as its less disruptive than ex situ
- chances of population recovering greater than ex situ
in situ conservation - disadvantages
difficult to control factors
- poaching
- predators
- disease
- climate change
ex situ conservation - what?
off-site conservation
protecting a species by removing part of the population from a threatened habitat and placing it in a new location
(often a last resort)
ex situ conservation - methods
- relocating an organism to a safer area
- eg. 5 white rhinos were recently relocated from Congo to Kenya because they were in danger of poachers who killed them for their ivory - breeding organisms in captivity and then reintroducing them into the wild
- carried out in animal sanctuaries and zoos - botanic gardens - controlled environments used to grow a variety of rare plants for conservation, research, display, and education
- endangered/extinct plant species can be grown and then reintroduced - seed banks - seeds can be frozen and stored in seed banks for over a century without losing their fertility
- provide a useful source of seeds if natural reserves are destroyed (disease or natural disasters)
ex situ conservation - advantages
- factors easy to manage because it’s a controlled environment
- predation
- hunting
- disease - also can be used to reintroduce a species that have left an area
ex situ conservation - disadvantages
- only a small no. of individuals can be cared for
- difficult and expensive to create and sustain the right environment
- animals that are used to human contact less likely to exhibit natural behaviour
- and more likely to catch diseases from humans - usually less successful than in situ methods
- many species cant breed successfully in captivity or cant adapt to new environment when moved to a new location
Rio Convention on Biological Diversity (CBD)
aims to develop international strategies for the conservation of biodiversity and how to use animal and plant resources in a sustainable way
the convention made it part of international law that conserving biodiversity is everyone’s responsibility
it also provides guidance to governments on how to conserve biodiversity
Convention on International Trade in Endangered Species (CITES)
an agreement designed to increase international cooperation in regulating trade in wild animal and plant specimens
the member countries all agreed to make it illegal to kill endangered species
the agreement helps to conserve species by limiting trade through licensing, nd by making it illegal to trade in products from endangered animals (rhino ivory and leopard skins)
its also designed to raise awareness of threats to biodiversity through education
why is international cooperation important in species conservation?
it would be pointless making hunting endangered species illegal in one country of poachers could just go and hunt them in another country
Local conservation agreements - The Countryside Stewardship Scheme (CSS)
introduced in 1991
aims to conserve wildlife and biodiversity and to improve and extend wildlife habitats by promoting specific management techniques to landowners
the government offered 10-year agreements to pay landowners who followed management techniques they were suggesting
- regenerate hedgerows, leave grassy margins around the edges of fields where wildflowers could grow, and graze upland to keep down bracken
in 2000 - 10 000 agreements in England
- since the introduction of the scheme various species have begun to rebuild in numbers.
